1. Field of the Invention
This invention relates to adjustable dies for cutting sheet materials such as sheet metal, and more particularly to an adjustable die for transversely shearing sheet material from a continuous strip with angled cuts.
2. Description of the Prior Art
There are many instances where it becomes desirable to cut nonrectangular polygonal pieces of sheet material from a long strip. In the manufacture of large nonrectangular panels for automobiles or large appliances, for example, each piece can be formed by rotating a rectangular blank in a single fixed die set and making a series of individual cuts in the blank. Alternatively, each blank can be passed through a series of fixed die sets, each die set making a single cut in the blank.
Also, a particular shape approximating a polygonal pattern of the part actually required can be cut from a continuous strip of sheet material in a single step by a fixed die set predesigned and manufactured to cut the desired shape. A fixed die set of this type represents a considerable saving of time and labor over forming the pieces from rectangular blanks, but such equipment is very costly and occupies much space.
Adjustable dies for cutting nonrectangular shapes out of sheet material are known. Vamp throating dies, for example, have been long used in the manufacture of shoes for cutting curved patterns out of sheet material, primarily leather. Adjustable corner shears are also known for cutting notches, or obtuse t angled to acute angled corners from sheet metal.
U.S. Pat. No. 4,483,227 issued to Camisa on Nov. 20, 1984 discloses such a corner shearing machine. The device in Camisa has a pair of upper and a pair of lower knives which interact in the manner of scissors. To form an angular cutting edge, one knife of each pair is placed against the other in a V-shaped manner. Each pair is supported on knife carriers which pivot about a vertical axis. The apparatus provides for adjusting the angle between the cutting edges, wherein each upper knife is connected positively, without the shear stroke being impeded, to the corresponding lower knife by an unbiased engagement piece.
A disadvantage of these known devices is that they cannot cut a continuous strip of sheet material transversely from one edge to another. Furthermore, such devices cannot be used in a conventional punch press which can rapidly make consecutive cuts, and also generate large forces on each shear stroke.
It is desirable, then, to provide an adjustable die set for transversely shearing sheet material in a punch press, which can also make angled cuts at high speed, and can absorb the large forces generated by the punch press.